930 resultados para Bleaching gels
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Coral bleaching has been increasingly the focus of research around the world since the early 1980s, when it was verified to be increasing in frequency, intensity and amount of areas affected. The phenomenon has been recorded since 1993, associated with elevation of the sea surface temperature due to El Niños and water thermal anomalies, according to most reports around the world. On the coast of Rio Grande do Norte, Brazil, a mass coral bleaching event was recorded in the Environmental Protection Area of Coral Reefs (APARC) during March and April 2010, when the water temperature reached 34°C for several days. About 80% of the corals in Maracajaú reef-complex exhibited partial or total bleaching. The aims of this study were to verify representativeness of coral coverage and how the bleaching dynamic has developed among different species. Coral coverage was estimated according to Reef Check Brazil protocol associated with quadrant method, and bleaching was evaluated from biweekly visual surveys in 80 colonies of Favia gravida, Porites astreoides, Siderastrea stellata and Millepora alcicornis. At the same time temperature, pH, salinity and horizontal transparency, as well as mortality and disease occurrence were monitored. Analysis of variance and Multiple Regression from the perspective of time lag concept were used to evaluate the bleaching dynamics among species and the relationship between variation of means of bleaching and variations of abiotic parameters, respectively. Species showed significant differences among themselves as to variation of means of bleaching over time, but the dynamic of variation exhibited similar patterns
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Neste trabalho, a técnica de PCR (polymerase chain reaction) foi utilizada para a sexagem de 92 embriões bovinos fertilizados in vitro. Os embriões originaram-se de fertilização in vitro de oócitos aspirados de ovários de fêmeas bovinas, provenientes de abatedouros comerciais. Os oócitos foram maturados, fertilizados e cultivados até o estádio de blastocisto. Os embriões foram lavados em solução de PBS, transferidos para tubos de polipropileno contendo água ultrapura, e imediatamente congelados a -196ºC. Os embriões foram descongelados sobre isopor contendo gelo picado e tratados com proteinase K. Para a reação de PCR, utilizaram-se alíquotas de 34 µl de cada tudo, onde foram acrescidos dois pares de primers, seqüência BC1.2 e seqüência satélite 1.715, desoxinucleotídeos, MgCl2, tampão PCR 10X, TaqDNA polimerase e água, em um volume final de 50 µl. As amostras foram amplificadas e a eletroforese realizada em gel de poliacrilamida a 8%. Os géis foram corados com solução de brometo de etídio e analisados em transiluminador de luz ultravioleta. Um índice de 93,47% de amplificação foi atingido, com 41 embriões (47,67%) machos e 45 (52,32%) embriões fêmeas. O uso de gel de poliacrilamida a 8% foi eficaz na separação de fragmentos de DNA muito próximos.
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The study analyzed the wood basic density effect in two Eucalyptus grandis x Eucalyptus urophylla hybrid clones (440 kg/m(3) e 508 kg/m(3)) on bleached pulp quality (fiber dimensions and physical-mechanical properties). The woods performance on pulping, bleaching and beating results were analyzed. The Kraft pulping was carried out in forced circulation digester in order to obtain 17 +/- 1 kappa number targets. The pulps were bleached to 90 +/- 1 using delignification oxygen and D0EOPD1 bleaching sequence. Bleached pulp of low basic density clone showed, significantly, lowest revolutions number in the PFI mill to reach tensile index of 70 N.m/g, low Schopper Riegler degree and generated sheets with higher values to bulk and opacity. These characteristics and properties allow concluding that bleached pulp of low basic density clone was the most indicated to produce printing and writing sheets. The bleached pulp of high basic density clone showed higher values of bulk and capillarity Klemm and lower water retention value when analyzed without beating. The bleached pulp of high basic density clone showed more favorable characteristics to the production of tissue papers.
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Cellulose was extracted from lignocellulosic fibers and nanocrystalline cellulose (NC) prepared by alkali treatment of the fiber, steam explosion of the mercerized fiber, bleaching of the steam exploded fiber and finally acid treatment by 5% oxalic acid followed again by steam explosion. The average length and diameter of the NC were between 200-250 nm and 4-5 nm, respectively, in a monodisperse distribution. Different concentrations of the NC (0.1, 0.5, 1.0, 1.5, 2.0 and 2.5% by weight) were dispersed non-covalently into a completely bio-based thermoplastic polyurethane (TPU) derived entirely from oleic acid. The physical properties of the TPU nanocomposites were assessed by Fourier Transform Infra-Red spectroscopy (FTIR), Thermo-Gravimetric Analysis (TGA), Differential Scanning Calorimetry (DSC), X-Ray Diffraction (XRD), Dynamic Mechanical Analysis (DMA) and Mechanical Properties Analysis. The nanocomposites demonstrated enhanced stress and elongation at break and improved thermal stability compared to the neat TPU. The best results were obtained with 0.5% of NC in the TPU. The elongation at break of this sample was improved from 178% to 269% and its stress at break from 29.3 to 40.5 MPa. In this and all other samples the glass transition temperature, melting temperature and crystallization behavior were essentially unaffected. This finding suggests a potential method of increasing the strength and the elongation at break of typically brittle and weak lipid-based TPUs without alteration of the other physico-chemical properties of the polymer. (C) 2012 Elsevier Ltd. All rights reserved.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Chitin and chitosan are nontoxic, biodegradable and biocompatible polymers produced by renewable natural sources with applications in diverse areas such as: agriculture, textile, pharmaceutical, cosmetics and biomaterials, such as gels, films and other polymeric membranes. Both have attracted greater interest of scientists and researchers as functional polymeric materials. In this context, the objective of this study was to take advantage of the waste of shrimp (Litopenaeus vannamei and Aristeus antennatus) and crabs (Ucides cordatus) from fairs, beach huts and restaurant in Natal/RN for the extraction of chitin and chitosan for the production of membranes by electrospinning process. The extraction was made through demineralization, deproteinization, deodorization and deacetylation. Morphological analyzes (SEM and XRD), Thermal analysis (TG and DTG), Spectroscopy in the Region of the Infrared with Transformed of Fourier (FTIR) analysis Calorimetry Differential Scanning (DSC) and mechanical tests for traction were performed. In (XRD) the semicrystalline structure of chitosan can be verified while the chitin had higher crystallinity. In the thermal analysis showed a dehydration process followed by decomposition, with similar behavior of carbonized material. Chitosan showed temperature of maximum degradation lower than chitin. In the analysis by Differential Scanning Calorimetry (DSC) the curves were coherent to the thermal events of the chitosan membranes. The results obtained with (DD) for chitosan extracted from Litopenaeus vannamei and Aristeus antennatus shrimp were (80.36 and 71.00%) and Ucides cordatus crabs was 74.65%. It can be observed that, with 70:30 solutions (v/v) (TFA/DCM), 60 and 90% CH3COOH, occurred better facilitate the formation of membranes, while 100:00 (v/v) (TFA/DCM) had formation of agglomerates. In relation to the monofilaments diameters of the chitosan membranes, it was noted that the capillary-collector distance of 10 cm and tensions of 25 and 30 kV contributed to the reduction of the diameters of membranes. It was found that the Young s modulus decreases with increasing concentration of chitosan in the membranes. 90% CH3COOH contributed to the increase in the deformation resulting in more flexible material. The membranes with 5% chitosan 70:30 (v/v) (TFA/DCM) had higher tensile strength
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The objective of this research is the fabrication of a composite reinforced with dyed sisal fiber and polyester matrix for application in the fields such as, fashion, clothing, interior textiles; fashion accessories are some of the examples. For the fabrication of the composite, the sisal fibers were subjected to processes such as: chemical treatment with sodium hydroxide (NaOH) in the removal of impurities; bleaching for removing the yellowish color of the natural fiber and dyeing with direct dyes to confer the colors blue, green and orange. The search for new technologies ecologically correct has become a major concern in recent decades. Studies show that composite polymer reinforced by natural fibers is suitable for a large number of applications, and its use is advantageous in terms of economic and ecological. The dyed fibers were cut to a length of 30 mm, is used in the confection of webs. For this purpose, a web preparer by immersion, developed in the Laboratory of Chemical Textile of UFRN. The composite sheets measuring 300 x 300 x3 mm were molded by compression, with unsaturated orthophthalic polyester as matrix, and the samples in sizes 150 x 25 x 3 mm were cut with the aid of a laser machine, to be subjected to traction and flexion. The mechanical properties of traction and flexion in three points were performed in the Laboratory of metal and mechanical tests of Materials Engineering of UFRN. The resulting samples from the tests were evaluated in scanning electron microscope (SEM) at CTGas RN. On the basis of the analysis of the results from the mechanical tests, it was observed that the composite had good mechanical behavior, both in traction as in flexion. Furthermore, it was observed that in the water absorption test, the samples had a different percentage among themselves, this occurred due to the variation of density found in the fibre webs. The images of the SEM showed the failures from the manufacturing process and the adhesion of fibre/matrix. When the samples were prepared with the dyed fibers to be applied in fashion, the results were positive, and it can be concluded that the main objective of this work was achieved
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Lotes de sementes de braquiária comercializados no Brasil vem apresentando contaminações com sementes de outras espécies pertencentes ao mesmo gênero. Deste modo, uma das espécies de braquiária atuaria como planta infestante da outra no agroecossistema e a erradicação da espécie infestante seria dificultada pela agressividade característica do gênero e pela falta de seletividade dos herbicidas disponíveis no mercado. Esses fatores ressaltam a importância da comercialização e utilização de lotes de sementes isento de sementes de outras espécies e a utilização de metodologias precisas de identificação das principais espécies de braquiária no controle de qualidade das empresas produtoras de sementes. Neste trabalho, buscou-se avaliar o potencial discriminante da técnica de eletroforese, utilizando quatro sistemas enzimáticos presentes em plântulas de quatro espécies do gênero Brachiaria, quer sejam B. brizantha cv. Marandu, B. decumbens cv. Basilisk, B. humidicola cv. comercial e B. plantaginea. Foram realizadas análises de eletroforese de isoenzimas testando-se 50 indivíduos de cada espécie por tratamento, utilizando-se coleóptilos de plântulas obtidas a partir de sementes germinadas a 30°C, no escuro. Para a eletroforese foi utilizado como meio suporte géis de poliacrilamida, nas concentrações de 7,0 e 7,5%. As isoenzimas Glutamato desidrogenase e Glucose-6-fosfato desidrogenase, embora eficientes na diferenciação entre B. plantaginea e B. humidicola e entre as sementes dessas espécies e as de B. brizantha ou B. decumbens, não se mostraram capazes de diferenciar as sementes destas duas últimas espécies. Entretanto, as izoenzimas α- e β-esterase possibilitaram uma nítida diferenciação das quatro espécies de Brachiaria estudadas.
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O trabalho foi realizado com o objetivo de avaliar o desempenho de Brachiaria ruziziensis cultivada em consórcio com milho safrinha, mediante a utilização dos herbicidas atrazine (1.760 g i.a. ha-1), mesotrione (60 g i.a. ha-1), mesotrione + atrazine (1.760 e 60 g i.a. ha-1) e nicosulfuron (8 e 16 g i.a. ha-1), aplicados aos 14 e 24 dias após a emergência das plantas de braquiária. O milho foi semeado mecanicamente no dia 7/3/2008 em linhas de 0,90 m, com uma linha intercalar de B. ruziziensis. O atrazine não causou sinais visíveis de toxicidade nas folhas de B. ruziziensis, enquanto o mesotrione causou branqueamento das pontas das folhas, mas proporcionou retomada rápida do crescimento. O nicosulfuron provocou clorose foliar, com necrose e redução do crescimento, sem recuperação total das plantas de B. ruziziensis durante o crescimento do milho, ocasionando baixo rendimento de massa da forrageira. Os colmos velhos, crescidos durante o cultivo do milho, são responsáveis pelo maior rendimento de massa da braquiária e são pouco afetados pelo atrazine e mesotrione, que podem ser utilizados no cultivo consorciado. O rendimento de grãos do milho safrinha não foi alterado significativamente pelos tratamentos.
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In this work, cellulose nanofibers were extracted from banana fibers via a steam explosion technique. The chemical composition, morphology and thermal properties of the nanofibers were characterized to investigate their suitability for use in bio-based composite material applications. Chemical characterization of the banana fibers confirmed that the cellulose content was increased from 64% to 95% due to the application of alkali and acid treatments. Assessment of fiber chemical composition before and after chemical treatment showed evidence for the removal of non-cellulosic constituents such as hemicelluloses and lignin that occurred during steam explosion, bleaching and acid treatments. Surface morphological studies using SEM and AFM revealed that there was a reduction in fiber diameter during steam explosion followed by acid treatments. Percentage yield and aspect ratio of the nanofiber obtained by this technique is found to be very high in comparison with other conventional methods. TGA and DSC results showed that the developed nanofibers exhibit enhanced thermal properties over the untreated fibers. (C) 2010 Elsevier Ltd. All rights reserved.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Maytenus ilicifolia is an important plant with potential on cancer treatment and has been largely used in Brazil and other countries. We have evaluated the crude ethanolic extract of M. ilicifolia as a potential antioxidant source using an assay based on the bleaching of the radical monocation 2,2'-azinobis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS(center dot+)) and by HOCl scavenger capacity. Trolox and uric acid were used as positive controls. The results indicated M. ilicifolia root bark as a great source of antioxidants based on its potential as scavenger of radicals. (c) 2006 Elsevier B.V. All rights reserved.
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The virulence of Paracoccidioides brasiliensis can be attenuated or lost after long periods of repeated subculturing and reestablished after animal inoculation. Only one adhesin (gp43) has been described until now, among the various identified components of P. brasiliensis, and gp43 shows adhesion to laminin. Thus, the present study was designed to isolate and characterize factors putatively related to the capacity of this fungus to adhere to the host by comparing P brasiliensis samples, taken before and after animal inoculation. The two samples differed in their pattern of adhesion and invasion. The sample recently isolated from animals (Pb18b) demonstrated a greater capacity to adhere and to invade the Vero cells than the one subcultured in vitro (Pb18a). Extract from Ph18b also showed higher levels of protein expression than that from Pb18a, when two-dimensional electrophoresis gels were compared. A protein species of 30 kDa, pI 4.9, was more evident in the Pb18b extract and had properties of adhesin. Laminin, but none of the other extracellular matrix (ECM) components, such as fibronectin, collagen I and IV, bound specifically to the P. brasiliensis 30 kDa protein. The roles of 30 kDa and gp43 in cellular interactions were investigated and the adhesion of P. brasiliensis yeast cells was intensively inhibited by pre-treatment of epithelial cells with 30 kDa protein and gp43. Thus, this study presents evidence that adhesion capacity could be related to virulence, and that a 30 kDa adhesin accumulated differentially in samples with different levels of pathogenicity. This protein and its adhesion characteristics are being published for the first time and may be related to the virulence of P brasiliensis. (c) 2005 Elsevier SAS. All rights reserved.
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A superfície interna das bisnagas fabricadas com alumínio não revestido e revestido com resina epóxi, utilizadas para acondicionar cremes, pomadas, géis, etc., foram avaliadas quimicamente e por métodos microbiológicos correlacionados com a aderência de microrganismos. A prova da porosidade e da resistência à remoção da resina foi observada por meio do microscópio eletrônico de varredura (Topcon FM300) e estereoscópio Leica (MZ12) acoplado a Sistema de Digitalização de Imagens. Para avaliar a ação dos microrganismos foram utilizados corpos-de-prova esterilizados (discos de 10mm de diâmetro), imersos em caldo Mueller Hinton (Difco) e colocados em tubos de polipropileno com tampa de rosca (Corning). Foram inoculados tubos com meio de cultura para cada uma das suspensões bacterianas (10(9)UFC/mL) de Streptococcus agalactiae, Staphylococcus aureus, Acinetobacter lwoffii e Candida albicans, incubados a 37°C, sob agitação constante durante 12 dias. O meio de cultura era trocado a cada 3 dias. Após esse período, os corpos-de prova foram removidos, processados e observados em microscópio eletrônico de varredura JEOL-JSM (T330A). A observação por meio do microscopio eletrônico de varredura mostrou a aderência e a formação de biofilme sobre a superfície de alumínio não revestido e revestido com resina epóxi.